Display time in munites

Hi,

I have two columns which I need to add together then devide by 60 in order to display that time in minutes. the problem I am facing is that at times I get numbers above 60 and my client doesn't want to see numbers above 60.

i.e (col1 + col 2)/60 = 34.87

what I need to do is make sure that when the number reaches 60 it moves on to 35.